Snap operating mechanism



y 1935- c. T. EVANS 2,000,322

SNAP OPERATING MECHANI SM Filed May 1, 1933 2 Sheets-Sheet l y 12935- c. T. EVANS I 2,000,322

SNAP OPERATING MECHANI SM Filed May 1, 1955 2 Sheets-Sheet 2 Patented May 7, 1935 UNITED STATES PATENT ()F'FICE SNAP OPERATING-VMECH'ANISM" Clarence T. Evans, Wauwa tosa assignor to.

Cutler-Hammer, Inc Milwaukee, Wis, a corporation of Delaware Application May I, 1933", No. 668,7 81,

6 Claims.

This invention relates to improvements in snap operating mechanisms for control devices such as crane limit switches.

Anobject of the present invention is to provide a simplified and generally improved snap operating mechanism for control devices such as crane limit switches.

Another object is to provide a snap operating mechanism of the aforesaid" character which is of the weight operated type and which provides for positive locking of its associated control device inopposite extreme positions.

Various other objects and advantages of the invention will hereinafter appear. g

The accompanying drawings illustrate an embodiment of the inventionwhich will now be described; itbeing understood that the embodiment illustrated may be modified invarious respect's without departing from the spirit and scope of the appended claims. In the drawings,

1 is a front elevational' view" of a limit switch having an operating mechanism embodying'the invention associated therewith, an'enclosing cover for such mechanism being shown in Fig. 2 isa top view ofthe operating mechanism shown in Fig. 1-, the enclosing coverior such mechanism and portions of the enclosing casing for the limit switch being shown in section.

" Fig. 3isa perspective view ofone'of the operating. parts shown in Figs. 1 and 2.

Fig.4 is a vertical", sectional view of the limit switchshownin Figs. 1 and'2'.

Figs. 5, 6; '7 and 8' are schematic views of the operating mechanism, illustrating the same in different positions, and

Fig. 9 is a diagrammatic view illustrating applicationof' the limit switchto the hoisting mechanism of an electric crane;

Referring to'Figs; l and? of thedrawings, thesame illustrate a control switch l provided with air-square operating shaft 2 which is rotatable in opposite directions between given extreme cir 45 cuit' controlling positions. Shaft 2. has an operating mechanism associated therewith including a lever 31 which is fixed to said shaft." a; latching mechanism. I which cooperates said lever to lock said shaft in" its extreme circuit controlling positions and a weighted operating arm 5' supported" by said lever and operatiyely connected. thereto by link 6'. As hereinafter set forth arm 5. is movable in opposite directions with respect 4 tolever 3 to-bias shaft 2 formovement oppo site directions between its extreme circuit con-- trolling positions, and the latching mechanism 4" is controlled by the arm 5 to provide for operation of said shaft between such positions with a snap action.

More specifically, control switch I is provided with an enclosing casing I having suitable hear-- ing' parts on opposite ends thereof for supporting' shaft I. As shown in Fig. 2; the front end of shaft F is supported by a ball bearing 8 carried by plate 9 secured to the front-wall of cas- 1 log 1 by screws Ill. Lever 3 1s mounted upon a forwardly projecting portion of shaft 2, and asshown in Pig. 3 said lever provided witha hub H having a square opening therein for receiving said shaft. Also as shown in Fig. 3-, the hub lo 15 has a pair of spaced horizontally arranged arms Il -l2 on one side thereof, a projecting log [-3 on its opposite side and a vertically arranged arm HI on its upper side.

Arm M cooperateswith the latching mecha 20 ism 4, and as shown in Figs. 1 and 2 said latching mechanism 4 includes a horizontally arranged lever l5 having its right hand end rotatably mounted upon a pin Hi fixed to plate 9 and hav ing a forked portion F1 on its left hand end which 5 carries a pinl8- having a roller I9 mounted thereon. Roller F9 cooperates with the upper end of the arm M on lever 3, and as shown in Fig. 3 said arm has concave faces 20-20 onopposite sides thereof for receiving said roller, and the end thereof is shaped to'providean inverted.- V-sha-ped face H. A spring 22 normally holds lever F5 in engagement with a stop 23, said spring being held under compression between said step, and a downwardly projecting lug 24 on the under of said lever. Stop 23 is fixed to the front face-oi plate 9 and is located so as to hold lever F5 inposition for engagement of roller l9 with the concave faces 2020 on arm M.

As hereinbefore stated, the weighted operating arm 5 issupported by lever 3 and is operatively connected thereto by the link 6. Link 6 is arranged above the hub portion H of lever 3 and the left hand end' thereof is rotatably" mounted upona-pi'vot pin 25* carried by the arms tZ-JZ' of said lever while the right hand end thereof abuts the upper'face oi the lugl'3. Arm 5 is arranged above the link 6 and is rotatably mounted at a point. intermediate its end's upon a pivot pin 26- carried by the right hand end of link 6'. The u-n- 5o derside of'arm 5 and theleft hand end of link- 6 are provided with abutting projections: 21 and 28 and said arms carriesa pair of screw stops 2'9 and 38 on the upper side thereoffor engagement with lever l5. Plate 9 is'provi'ded with steps 31 and 32 for limiting movement of the right hand end of arm 5 in opposite directions, and the right hand end of said arm is provided with an eye projection 33 for receiving a cable connection 34,

while the left hand end thereof is provided with a weighted projection 35.

The function and operation of the aforedescribed mechanism will now be more fully described in connection with Figs. 5 to 9, inclusive. The control switch 1 may be of a type commonly employed on electric cranes to limit upward movement of the hoist block and in such installa tions a counterweight 36 is suspended from the right hand end of arm 5, as shown in Fig. 9, to

normally hold said arm in the position shown in Figs. 1 and 5. As shown in Fig. 9 the hoist block 31 is adapted to be raised and lowered by a mechanism including a cable 38 and winding drum 39 and upon movement of the hoist block into its upper limit the same engages counterweight 36 to raise the same and permit counterclockwise movement of arm 5 under the action of its weighted projection 35. 7

When the arm 5 is in the position shown in Figs. 1 and 5, roller IQ of the latching mechanism 4 engages the left hand concave face 20 on arm l4 and lever 3 is thus held against counterclockwise rotation to lock shaft 2 against movement out of one extreme position. During movement of the hoist block 3'! into its upper limit counterweight 36 is raised and arm 5 then moves in a counterclockwise direction under the action of its weighted projection 35 towards the position shown in Fig. 7. During such movement of arm 5 link 6 rocks therewith upon pivot pin 25, and as is apparent from Fig. 6 the entire Weight of arm 5 is then supported upon said pivot pin. Thus the weight of arm 5 tends to effect counterclockwise movement of lever 3, such movement being prevented pending movement of said arm into the extreme position shown in Fig. 7. During final movement of arm 5 into the extreme position shown in Fig. '7 the stop 30 on said arm engages lever [5 to move the same upwardly for release of roller l9 with the left hand face 20 on arm [4. The weight of arm 5 then acts to effect snap movement of lever 3 and shaft 2 from the extreme position shown in Fig. 6 into the extreme position shown in Fig. 7. Upon movement of the lever 3 into the position shown in Fig. 7 lever l5 of the latching mechanism is moved downwardly by its associated spring 22 and roller 19 then engages the concave face 20 on the right hand side of arm l4to positively lock lever 3 and shaft 2 against movement in a clockwise direction.

Upon lowering of the hoist block 31 out of its upper limit counterweight 36 acts to return arm 5 from the position shown in Fig. 7 to the position shown in Fig. 5. During such movement of arm 5 the same rotates upon pivot pin 26, and as is apparent from Fig. 8 the entire weight of said.

arm is then supported upon lug l3.. Thus the weight of arm 5 tends to move lever 3 in a clock wise direction, such movement being prevented.

' therefor.

said lever and said shaft against counterclockwise movement.

The control switch I may be of the type illustrated in Fig. 4. As shown in this figure an insulating base 40 is secured to the bottom wall of a frame 4| which forms a part of the switch enclosing casing 1. The switch mechanism includes a plurality of normally closed switches for controlling hoisting power connections for the hoist motor and a plurality of normally'open switches for controlling dynamic braking connections The stationary contacts of said switches are mounted upon the upper face of base 48 and the movable contacts thereof are mounted upon shaft 2. Each of the normally closed switches is provided with a stationary contact 42 and a cooperating movable contact 43 which are arranged to the right of shaft 2 while each of the normally open switches is provided with a stationary contact 44 and a cooperating movable contact 45 which are arranged to the left .of shaft 2. As is apparent, when the above described operating mechanism is in the normal position shown in Figs. 1 and 5 the switches are maintained in the positions shown in Fig. 4 to establish power connections for the hoisting motor. However, upon movement of the operating mechanism into the position shown. in Fig. '7 the contacts 42 and 43 of the normally closed switches are disengaged to interrupt power connections for the hoist motor and contacts 44 and 45 of the normally open switches are moved into engagement to establish dynamic braking connections therefor.

What I claim as new and desire to secure by Letters Patent is:

1. The combination with a control device having' an operating shaft rotatable in opposite directions between given extreme positions, of a latching mechanism associated with said shaft for locking the same against movement out of either of said extreme positions and a-weighted operating member arranged above said shaft and supported thereby, said member being movable in opposite directions with respect to said shaft and being adapted to act by gravity when moved in either direction with respect to said shaft to bias the same in a corresponding direction, and said latching mechanism being releasable by said operating member upon movement of the latter in opposite directions into given extreme positions.

2. The combination with a control device having an operating'shaft rotatable in opposite directions between given extreme positions, a latching mechanism associated with said shaft for locking the same against movement out of either of said extreme positions, and an operating member arranged to one side of said shaft and'normally supported by said shaft at points on opposite sides of the axis thereof, said operating member being movable in opposite directions with respect to said shaft to cause the same to actat either of said points for biasing of said shaft in either direction between saidextreme positions, and said latching mechanism being releasable by said operating member to provide for snap movements of said shaft in opposite directions between said extreme positions under the biasing action of said operating member.

3. The combination with a control device hawing a horizontally arranged operating shaft rotatable in opposite. directions between given extreme positions, a latching mechanism associated with said shaft for locking the same against movement out of either of said extreme positions, a lever fixed to said shaft and having horizontally arranged arms on opposite sides of the axis thereof, a link arranged above said shaft having one end pivotally connected to one of said arms, and a weighted operating arm pivotally connected to the opposite end of said link and normally supported upon opposite sides of the axis of said shaft by the arms on said lever, said operating arm being movable in opposite directions with respect to said shaft to shift the weight thereof to either of the arms of said lever to effect biasing of said shaft for rotation in either direction between said extreme positions, and said latching mechanism being releasable by said operating arm to provide for snap movements of said shaft in opposite directions between said extreme positions under the biasing action of said operating arm.

4. The combination with a control device having a horizontally arranged operating shaft rotatable in opposite directions between given extreme positions, of a latching mechanism associated with said shaft for locking the same against movement out of either of said extreme positions, and an actuating lever carried by said shaft and normally supported at points upon opposite sides of the axis thereof, said lever being movable in opposite directions with respect to said shaft and in a plane at right angles to the axis thereof to cause the entire weight of said lever to act at either of said points for biasing of said shaft in either direction between said extreme positions and said latching mechanism being releasable by said actuating lever to provide for snap movement of said shaft in opposite directions between said extreme positions under the biasing action of said lever.

directions with respect thereto to cause the same.

to act by gravity on said member at points on opposite sides of the axis thereof for biasing of said member in either direction between said extreme positions, said latching mechanism being releasable by said actuating member to provide for snap movement of said control part in opposite directions between said extreme positions under the biasing action of said actuating part.

6. The combination with a control device having a control part requiring movement in opposite directions between given extreme positions, of a weighted operating lever-supported by said control part and movable in opposite directions with respect thereto, said operating lever when moved in either direction with respect to said control part being adapted to bias the latter in a corresponding direction, and a latching mechanism associated with said control part for positively locking the same against movement out of either of said extreme positions, said latching mechanism being releasable directly by said operating lever to provide for snap movement of said control part in opposite directions between said extreme positions under the biasing action of said operating part.

CLARENCE T. EVANS. 

